Filament holder for hot cathode pecvd source

ABSTRACT

A chemical vapor deposition source that includes at least one plate to which first and second electrical connection posts are coupled. The chemical vapor deposition source also includes a filament having a first end and a second end. The first end of the filament is electrically connected to the first electrical connection post and the second end of the filament is electrically connected to the second electrical connection post. The chemical vapor deposition source further includes at least one filament holder electrically insulated from the at least one plate. The at least one filament holder holds a portion of the filament between the first end and the second end.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims the benefit of U.S.provisional patent application Ser. No. 62/088,345, filed Dec. 5, 2014,the content of which is hereby incorporated by reference in itsentirety.

BACKGROUND

Data storage systems commonly have one or more data storage media andone or more elements (for example, read/write heads) that communicatewith the data storage media to store and retrieve data. Data storagemedia may be magnetic storage media, optical storage media, etc.Magnetic storage media such as magnetic discs may comprise a substrateover which a non-magnetic underlayer, a magnetic layer and a protectiveovercoat are deposited using a suitable technique.

A plasma enhanced chemical vapor deposition (PECVD) technique may beused to deposit the protective overcoat. This technique may employ adeposition source having a filament for emitting electrons.

SUMMARY

The present disclosure relates to filament holders that are capable ofrestraining/limiting filament movement. Certain embodiments relate tofilament holders and other related elements used in a process fordepositing a protective overcoat on a data storage medium. In oneembodiment, a chemical vapor deposition source that includes at leastone plate to which first and second electrical connection posts arecoupled is provided. The chemical vapor deposition source also includesa filament having a first end and a second end. The first end of thefilament is electrically connected to the first electrical connectionpost and the second end of the filament is electrically connected to thesecond electrical connection post. The chemical vapor deposition sourcefurther includes at least one filament holder electrically insulatedfrom the at least one plate. The at least one filament holder holds aportion of the filament between the first end and the second end.

Other features and benefits that characterize embodiments of thedisclosure will be apparent upon reading the following detaileddescription and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view showing a filament, at least one filamentholder and plates of a deposition source in accordance with oneembodiment.

FIG. 1B is a perspective view showing a filament, at least one filamentholder and plates of a deposition source in accordance with anotherembodiment.

FIG. 2 is a diagrammatic illustration that shows a schematic sidesectional view of a single chemical vapor deposition source of adeposition tool.

FIG. 3A is a diagrammatic illustration that shows a schematic sidesectional view of a deposition tool that includes two chemical vapordeposition sources of the type shown in FIG. 2.

FIG. 3B is a diagrammatic illustration of a surface of a media disc.

FIG. 4A is a sectional view that shows a filament holder in accordancewith one embodiment.

FIG. 4B is diagrammatic illustration showing a mounting of a diffuserplate included in the embodiment of FIG. 4A.

FIGS. 5A and 5B illustrate different views of a filament holder inaccordance with another embodiment.

FIGS. 6A and 6B illustrate different views of a filament holder inaccordance with yet another embodiment.

FIGS. 7A and 7B illustrate different views of multiple filament holdersin accordance with still another embodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The disclosure generally relates to filament holders that are capable ofrestraining/limiting filament movement. Certain embodiments describedbelow relate to filament holders and other related elements used in aprocess for depositing a protective overcoat on a data storage medium.

A plasma enhanced chemical vapor deposition (PECVD) process may be usedto deposit the protective overcoat on the data storage medium. The PEVCDprocess may employ a deposition source having a filament for emittingelectrons. In a particular embodiment, a chemical vapor depositionsource, which uses a hot filament cathode capable of emitting electronsby thermionic emission, is utilized in the PEVCD process to deposit acarbon overcoat on a magnetic data storage medium (for example, amagnetic data storage disc).

During operation of the chemical vapor deposition source, the filamentmay be heated to about 2500 K (degree Kelvin) to produce electrons bythermionic emission in vacuum. The high temperature combined with theforce of gravity may result in sagging of the filament. The carbonprocess may result in uneven carburization of the filament, whichcombined with the gravitational forces and the inherent stresses createdin the filament during its fabrication, may result in distortion of thefilament in multiple dimensions.

The carbon (media overcoat) uniformity is directly affected by theshape, position, and carburization of the filament that acts as theprimary electron source. Improved protective overcoat uniformityimproves both mechanical and electrical performance in a data storagedevice that includes the magnetic medium by, for example, reducingspacing variations between a read/write head and the medium.

FIG. 1A is a perspective view of a portion 100 of a single PECVD source.An entire single PECVD source is described further below in connectionwith FIG. 2. In the embodiment of FIG. 1A, PECVD source portion 100includes a filament 102A, electrical connection posts 104 and 106, atleast one filament holder 108, and multiple plates including a baseplate or rear plate 110, a source shield 111 and a diffuser plate 112.

Filament 102A is a conducting wire with a substantially high meltingpoint. Filament 102A includes a first end 114A and a second end 116Athat are electrically connected to posts 104 and 106, respectively. Bothfirst end 114A and second end 116A may be hook shaped or may be of anyother suitable shape depending on, for example, a shape/configuration ofpost 104, 106 to which the filament end 114A, 116A is to be connected.Rear plate 110 is vertically mounted in the PECVD source. Source shield111 is coupled to the rear plate 110, and diffuser plate 112 may becoupled to source shield 111 via insulating spacers (not shown in FIG.1A) that are described further below. Electrical connection posts 104and 106 are mounted on the rear plate 110. Details regarding the rearplate 110 and the diffuser plate 112 are provided further below inconnection with FIGS. 2 and 3.

As noted above, the embodiment of FIG. 1A includes filament holder 108.The filament holder 108 includes a fastening portion 118 that couples toa to diffuser plate 112 or to a suitable support member (not shown inFIG. 1A) behind diffuser plate 112. As will be described further below,when coupled to a support structure such as diffuser plate 112, filamentholder 108 may be electrically insulated from the source shield 111,which comprises an electrical ground plane of the PECVD source. As canbe seen in FIG. 1A, filament holder 108 further includes a holdingfeature 120 that holds a portion of the filament 102A at a locationbetween the first end 114A and the second end 116A in a manner thatprevents deformation of the filament 102A during its service life.Specifically, FIG. 1A shows a single filament holder 108 with theholding feature 120 positioned at a single bend in filament 102A.However, in an alternate embodiment, multiple filament holders 108 withrespective holding features 120 positioned at different bends infilament 102A may be employed. It should be noted that, when multiplefilament holders 108 are employed, individual ones of the multiplefilament holders 108 may be insulated from each other. In general,filament 102A may have any suitable shape, and any suitable number offilament holders may be utilized to hold the filament 102A.

FIG. 1B shows a filament 102B that has a shape that is different fromthe shape of filament 102A. Also, a first end 114B of filament 102B isconnected to a first post extender 122 and a second end 116B of filament102B is connected to a second post extender 124. First post extender 122is connected to first electrical connection post 104 and second postextender 124 is connected to second electrical connection post 106.Filament 102B includes a first curved arm 126 that extends from thefirst end 114B and a second curved arm 128 that extends from the secondend 116B. The arms 126 and 128 are connected via a central or transitionregion 130. A first end 132 of first curved arm 126 is held by a firstfilament holder 108A and a second end 134 of second curved arm 128 isheld by a second filament holder 108B. In other respects, theembodiments of FIGS. 1A and 1B are substantially similar and therefore adescription of the remaining components of source portion 100 is notrepeated in connection with FIG. 1B. It should be noted that filamentholders 108A and 108B may be similar to filament holder 108 of FIG. 1A.

FIG. 2 is a diagrammatic illustration that shows a schematic sidesectional view of a single PECVD source 200 of a carbon deposition toolthat includes portion 100 shown in FIG. 1B. The side sectional view isalong line A-A′ of FIG. 1B. PECVD source 200 is capable of depositing acarbon overcoat on one side of a two-sided media disc (not shown in FIG.2). As can be seen in FIG. 2, PECVD source 200 includes a first portion202 and a second portion 204. During operation of PECVD source 200, avacuum is established within first portion 202 and second portion 204 isat atmospheric pressure. First portion 202 is separated from secondportion 204 by base plate or rear plate 110 and source shield 111. Baseor rear pate 110 includes a gas inlet 206 through which a carboncontaining gas (for example, a hydrocarbon gas) is supplied duringoperation.

First portion or chamber 202 includes the diffuser plate 112 that helpsdiffuse the gas as it enters the first portion or chamber 202 throughthe gas inlet 206. Also included in first portion or chamber 200 are ananode 208 and filament 102B (the cathode). As described earlier inconnection with FIG. 1B, first end 114B of filament 102B is connected tofirst post extender 122 and second end 116B of filament 102B isconnected to second post extender 124. Also, as described earlier, firstpost extender 122 is connected to first electrical connection post 104and second post extender 124 is connected to second electricalconnection post 106. Electrical connection posts 104 and 106 and anode208 are mounted on base or rear plate 110. Electrical feedthroughs 210and 212 in second portion 204 are connected to base or rear plate 110.As described above in connection with FIG. 1B, first filament holder108A and second filament holder 108B hold portions of filament 102B. Inthe interest of simplification, any additional components/elements thatmay be included in PECVD source 200 are not shown or described.

FIG. 3A is a diagrammatic illustration that shows a schematic sidesectional view of a carbon deposition tool 300 that includes first andsecond PECVD sources 200A and 200B, which are substantially similar tothe PECVD source 200 described above in connection with FIG. 2.Therefore, a description of elements of individual sources 200A and 200Bis not provided.

A two-sided media disc 302 to be coated with a carbon overcoat on bothits sides is held between sources 200A and 200B by a support element304. In the interest of simplification, details of the support element304 are not provided. During operation, carbon containing gas issupplied to sources 200A and 200B in a manner described above inconnection with FIG. 2. Also, electrical current is run through bothfilaments 102B in both sources 200A and 200B. The electrical currentcauses the filaments 102B to heat and emit electrons by thermionicemission. The acceleration of those electrons results in plasma in eachof the sources 200A and 200B. Accordingly, in such an embodiment, thecarbon material that coats opposing surfaces of two-sided media disc 302is supplied by emitting electrons by thermionic emission from each PECVDsource. One surface of two-sided media disc 302 is shown in FIG. 3B. Asindicated above, during such a process, filament holders 108A and 108Bhold portions of the filament 102B at suitable locations such thatdeformation of the filament 102B is prevented. Therefore, by employingfilament holders 108A and 108B, the shape of filament 102B may besubstantially maintained through its lifetime. FIGS. 4A-7B illustratedifferent specific embodiments of filament holders.

FIG. 4A illustrates a filament holder 408 in accordance with oneembodiment. In filament holder 408, holding feature 420 includes a slot421 that is capable of holding a portion of a filament such a 102B.Fastening portion 418 of filament holder 408 includes threads forsecuring the filament holder 408 to diffuser plate 112, which includes acorresponding threaded hole (not shown in FIG. 4A) that is sized toreceiving the fastening portion 418 of filament holder 408. In theembodiment shown in FIG. 4A, filament holder 408 has a substantiallyuniform circular cross-section along a height of the filament holder 408along an axis 424. However, different configurations of filament holder408 may be used in different embodiments. In one embodiment, filamentholder 408 is formed of molybdenum and is electrically isolated from theground plane of the source (i.e., electrically isolated from sourceshield 111). In a particular embodiment, the electrical isolation iscarried out as shown in FIGS. 4A and 4B by using spacers 452 formed ofan insulator (for example, ceramic) to float diffuser plate 112 from itsrear side. Specifically, spacers 452 are positioned on sides of a bolt450 that passes through a hole in source shield 111. The bolt 450 isheld in place with the help of nut 454 and washer 456 that are shown inFIG. 4B. During operation, as the filament 102B heats up and expands, itwedges itself into the slot 420 and thus is captured and restrained frommoving in all three axes (i.e., x, y and z directions) over its servicelife. Thus, by capturing the filament 102B from the beginning of itslife, its position relative to a substrate is held and maintained toprovide a relatively uniform carbon film throughout its service life.

FIG. 5A illustrates a filament holder 508 in accordance with anotherembodiment. Filament holder 508 may be made of a same material (forexample, molybdenum) as filament 408 (of FIG. 4A) in some embodiments.In such embodiments, filament holder 508 is configured to have a massthat is substantially less than a mass of filament holder 408 (of FIG.4A). The lower mass results in a reduced heat sinking capability offilament holder 508 relative to a heat sinking capability of filamentholder 408 (of FIG. 4A). In the embodiment of FIG. 5A, the relativelylow-mass filament holder 508 includes a portion 525 that has asubstantially lower cross-section than a corresponding portion 425 offilament holder 408 (of FIG. 4A). Also, holding feature 520 is of asubstantially similar size as holding feature 420 (of FIG. 4A), butincludes multiple slots/grooves 521 and therefore has a reduced massrelative to holding feature 420 (of FIG. 4A), which has a single slot421. Fastening portion 518 of filament holder 508 is substantiallysimilar to fastening portion 418 (of FIG. 4A). Also, as can be seen inFIG. 5B, filament holder 508 is coupled to diffuser plate 112 in amanner similar to the above-described coupling between filament holder408 (of FIG. 4A) and diffuser plate 112 shown in FIG. 4A. Also, couplingbetween diffuser plate 112 and source shield 111 shown in FIGS. 4A and5B are substantially similar and therefore the description provided inconnection with FIG. 4A is not repeated for FIG. 5B.

FIGS. 6A and 6B illustrate a filament holder 608 in accordance with yetanother embodiment. As can be seen in FIG. 6B, filament holder 608includes a sleeve 617, a stud 618 and a tip 620. In one embodiment,sleeve 617 is formed of an insulating material (for example, alumina).Stud 618 may be formed of a metal such as stainless steel, and tip 620may be formed of tungsten or any other suitable material. As can be seenin FIG. 6B, tip 620 may be rod-shaped and may be located at a bentportion of filament 102A. In some embodiment, tip 620 may be a straightrod positioned substantially along, for example, axis 424. In otherembodiments, tip 620 may be curved, bent or tilted (i.e., at an angle)from axis 424 to help hold the bent portion of filament 102A in placeduring operation of the source. As can be seen in FIG. 6B, which is asectional view of the embodiment shown in FIG. 6A, stud 618 is mountedon an insert 624, which is behind diffuser plate 112 and betweendiffuser plate 112 and base plate 110. Insert 624, which may be formedof a suitable insulating material, may include, for example, threadedgroves 626 that are configured to receive threaded studs 618. It shouldbe noted that, in the embodiment of FIGS. 6A and 6B, sleeve 617 passesthrough a hole in diffuser plate 112 and therefore diffuser plate 112 isnot a part of the heat sink in this embodiment.

FIGS. 7A and 7B illustrate filament holders 708A-708E in accordance withstill another embodiment. In the embodiment shown in FIGS. 7A and 7B,each filament holder 708A, 708B, etc., is similar to filament holder 608of FIGS. 6A and 6B. However, in addition to including a first tipportion 620′, which is similar to tip 620 (of FIGS. 6A and 6B), tip 720of filament holder 708A, for example, further includes a second tipportion 722 that is at a suitable angle (for example, 90 degrees) tofirst tip portion 620′. The substantially L-shaped tip 720 helps holdthe bent portion of filament 102A in place during operation of thesource. Couplings shown in FIGS. 6B and 7B are substantially similar andtherefore the description provided in connection with FIG. 6B is notrepeated for FIG. 7B. As noted above, since multiple filament holders708A, 708B, etc., are employed, individual ones of the multiple filamentholders 708A, 708B, etc., may be insulated from each other.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Additionally, the illustrations are merely representational and may notbe drawn to scale. Certain proportions within the illustrations may beexaggerated, while other proportions may be reduced. Accordingly, thedisclosure and the figures are to be regarded as illustrative ratherthan restrictive.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to limit the scope of this applicationto any particular invention or inventive concept. Moreover, althoughspecific embodiments have been illustrated and described herein, itshould be appreciated that any subsequent arrangement designed toachieve the same or similar purpose may be substituted for the specificembodiments shown. This disclosure is intended to cover any and allsubsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

The Abstract of the Disclosure is provided to comply with 37 C.F.R.§1.72(b) and is submitted with the understanding that it will not beused to interpret or limit the scope or meaning of the claims. Inaddition, in the foregoing Detailed Description, various features may begrouped together or described in a single embodiment for the purpose ofstreamlining the disclosure. This disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may be directed toless than all of the features of any of the disclosed embodiments.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope of the present disclosure. Thus, to themaximum extent allowed by law, the scope of the present disclosure is tobe determined by the broadest permissible interpretation of thefollowing claims and their equivalents, and shall not be restricted orlimited by the foregoing detailed description.

What is claimed is:
 1. A chemical vapor deposition source comprising: atleast one plate; first and second electrical connection posts coupled tothe at least one plate; a filament having a first end and a second end,wherein the first end of the filament is electrically connected to thefirst electrical connection post and the second end of the filament iselectrically connected to the second electrical connection post; and atleast one filament holder electrically insulated from the at least oneplate, wherein the at least one filament holder is configured to hold aportion of the filament between the first end and the second end.
 2. Thechemical vapor deposition source of claim 1 and wherein the at least oneplate comprises a base plate to which the first electrical connectionpost and the second electrical connection post are coupled, and a sourceshield coupled to the base plate.
 3. The chemical vapor depositionsource of claim 2 and further comprising a diffuser plate coupled to thesource shield, wherein the source shield is between the base plate andthe diffuser plate.
 4. The chemical vapor deposition source of claim 3and wherein the at least one filament holder comprises a holding featureconfigured to hold the portion of the filament between the first end andthe second end and a fastening portion configured to couple to thediffuser plate, and wherein the diffuser plate comprises at least onereceptacle configured to receive the fastening portion.
 5. The chemicalvapor deposition source of claim 4 and wherein the diffuser plate iscoupled to the source shield via insulating spacers.
 6. The chemicalvapor deposition source of claim 4 and wherein the holding featurecomprises at least one slot configured to receive the portion of thefilament between the first end and the second end.
 7. The chemical vapordeposition source of claim 6 and wherein the filament holder comprises alength, and wherein a cross section of the filament holder issubstantially uniform along the length of the filament holder.
 8. Thechemical vapor deposition source of claim 6 and wherein the filamentholder comprise a length, and wherein a cross-section of the filamentholder is non-uniform along the length of the filament holder with arelatively small cross-section portion along a part of the length of thefilament holder.
 9. The chemical vapor deposition of claim of claim 3and wherein the at least one filament holder comprises a holding featureconfigured to hold the portion of the filament between the first end andthe second end and a fastening portion configured to couple to an insertbetween the diffuser plate and the base plate, and wherein the diffuserplate comprises at least one through hole for the fastening portion topass through to couple to the insert.
 10. The chemical vapor depositionsource of claim 9 and wherein the holding feature comprises a rod-shapedtip that is configured to support the portion of the filament betweenthe first end and the second end.
 11. The chemical vapor depositionsource of claim 9 and wherein the holding feature comprises asubstantially L-shaped tip that is configured to support the portion ofthe filament between the first end and the second end.
 12. The chemicalvapor deposition source of claim 4 and wherein the at least one filamentholder comprises a plurality of filament holders, and wherein individualones of the plurality of filament holders are electrically isolated fromeach other.
 13. An apparatus comprising: a filament holder comprising: afastening portion configured to couple to a support structure; and aholding portion configured to hold a portion of a filament that isbetween a first electrically coupled end of the filament and a secondelectrically coupled end of the filament.
 14. The apparatus of claim 13and further comprising: at least one plate; and first and secondelectrical connection posts coupled to the at least one plate, whereinthe first electrically coupled end of the filament is coupled to thefirst electrical connection post, and wherein the second electricallycoupled end of the filament is coupled to the second electricalconnection post.
 15. The apparatus of claim 14 and wherein the at leastone plate comprises a base plate to which the first electricalconnection post and the second electrical connection post are coupled,and a source shield coupled to the base plate.
 16. The apparatus ofclaim 15 and further comprising a diffuser plate coupled to the sourceshield, wherein the source shield is between the base plate and thediffuser plate, and wherein the diffuser plate comprises the supportstructure to which the fastening portion of the filament holder isconfigured to couple.
 17. The apparatus of claim 15 and furthercomprising: a diffuser plate coupled to the source shield; an insertbetween the diffuser plate and the base plate, wherein the insertcomprises the support structure, wherein the fastening portion isconfigured to couple to insert between the diffuser plate and the baseplate, and wherein the diffuser plate comprises at least one throughhole for the fastening portion to pass through to couple to the insert.18. A plasma enhanced chemical vapor deposition source comprising: atleast one plate; and at least one filament holder insulatingly coupledto the at least one plate, wherein the at least one filament holder isconfigured to hold a portion of the filament between a first end of thefilament and a second end of the filament.
 19. The plasma enhancedchemical vapor deposition source of claim 18 and wherein the at leastone plate comprises: a base plate; a source shield coupled to the baseplate; and a diffuser plate coupled to the source shield, wherein thesource shield is between the base plate and the diffuser plate.
 20. Theplasma enhanced chemical vapor deposition source of claim 19 and whereinthe at least one filament holder is mounted on the diffuser plate.